The use of photodynamic therapy for the treatment of cancer is a rapidly growing technique. Specifically the method depends on the incorporation of a photosensitizer (currently hematoporphyrin derivative [HpD]) into the tumor. Subsequent irradiation of the target tumor with light results in the generation of singlet oxygen, a reactive species which destroys the tumor. We have synthesized a new class of photosensitizers which have advantages over hematoporphyrin derivative. This class of compounds, called purpurins, absorb more efficiently than HpD at the longer wavelength of visible light currently used in the photodynamic treatment of cancer. Additionally, purpurins can be synthesized with a high degree of purity and with a known chemical structure. Our goals are to 1) synthesize purpurin analogues to be used for the photodynamic treatment of malignant tumors; 2) study the biologic effects on neoplastic tissue of these analogues when combined with visible light; 3) study the tissue distribution of these analogues; 4) study the biologic effects of these analogues on normal tissue when combined with visible light.